A user group consisting of twenty principal investigators and their research staff at Boston Biomedical Research Institute, working on more than twenty NIH-funded projects, is requesting funds for the purchase of a Procise Protein Sequencing System from Applied Biosystems. These investigators are conducting a wide range of research projects, which focus on topics such as protein-protein interactions and structure-function relationships of proteins in contractile systems and heat shock proteins, subunit interactions in membrane-associated energy transduction and transport systems, mechanisms of cell death and signaling pathways, the design of immunotherapeutic agents to treat Alzheimer disease, and the crystal structures of various proteins. The requested instrument is to replace a 12-year old ABI 477, which has recently become nonfunctional. An in-house sequencing facility is needed for the verification of protein and protein fragments generated by recombinant DNA techniques and the assessment of protein fragments for crystallographic studies. N-terminal sequencing in conjunction with mass spectrometry is also essential for studies involving identification of binding partners, determination of epitopes, identification of post-translational modification sites and determination of proximity relationships within or between proteins. The requested instrument will be housed in the Institute's Protein/Peptide Core Facility and will be supervised by Dr. Renne Lu, the director of the Core Facility. Dr. Lu and Ms. Ming-Jen Tsay will be the designated operators and responsible for the maintenance of the instrument. It is anticipated that research activities at BBRI will keep the instrument well utilized. However, scientists from other research institutions will also be given access to this instrument on an availability basis.